Microparticulate material

ABSTRACT

The present invention relates to microparticulate materials comprising nanoparticulate cores of inorganic material with oligomeric or polymeric structures containing non-acidic, nucleophilic groups on their surface, where the cores have been agglomerated via an interaction of the non-acidic, nucleophilic groups with at least one further constituent containing electrophilic groups. The present invention furthermore relates to catalysts built up from these materials, to processes for the production of these materials or catalysts, to the use of the catalysts for the polymerisation of olefins, and to a polymerisation process using the catalysts.

The present invention relates to micro- and nanoparticulate materials,to catalysts built up from these materials, to processes for theproduction of these materials or catalysts, to the use of the catalystsfor the polymerisation of olefins, and to a polymerisation process usingthe catalysts.

Metallocene-catalysed polymerisation has experienced an enormous upswingsince the beginning of the 1980s. Initially conceived as a model systemfor Ziegler-Nafta catalysis, it has increasingly developed into anindependent process with enormous potential for the (co)polymerisationof ethene and higher 1-olefins. Besides the activity-increasing use ofthe cocatalyst methylaluminoxane instead of simple trialkyl compounds,the crucial factor for the rapid development is the constant improvementin the activity and stereoselectivity due to systematic catalyststructure/activity relationships (G. G. Hlatky, Coord. Chem. Rev. 1999,181, 243; R. Mülhaupt, Nachr. Chem. Tech. Lab. 1993, 41, 1341).

However, homogeneous catalysts are of only limited suitability forlarge-scale industrial use in the gas or suspension polymerisationprocesses usually used. Agglomeration of the catalytically activecentres frequently occurs, with the consequence of caking on the reactorwalls, etc., known as “reactor fouling”. As a consequence, supportedcatalysts were therefore developed. The catalyst support is intended toavoid the said problems.

The support substances usually described here are based on inorganiccompounds, such as silicon oxides (for example U.S. Pat. No. 4,808,561,U.S. Pat No. 5,939,347, WO 96/34898) or aluminium oxides (for example M.Kaminaka, K. Soga, Macromol. Rapid Commun. 1991, 12, 367) orphyllosilicates (for example U.S. Pat. No. 5,830,820; DE-A-197 27 257;EP-A-849 288), zeolites (for example L. K. Van Looveren, D. E. De Vos,K. A. Vercruysse, D. F. Geysen, B. Janssen, P. A. Jacobs, Cat. Lett.1998, 56(1), 53) or on model systems, such as cyclodextrins (D. -H. Lee,K. -B. Yoon, Macromol. Rapid Commun. 1994, 15, 841; D. Lee, K. Yoon,Macromol. Symp. 1995, 97, 185) or polysiloxane derivatives (K. Soga, T.Arai, B. T. Hoang, T. Uozumi, Macromol. Rapid Commun. 1995, 16, 905).

A fresh problem which occurs on use of supports is the associatedreduction in the activity and selectivity of the catalyst compared withhomogeneous polymerisation.

Accordingly, there was a demand for materials which avoid thedisadvantages of the prior art on use in heterogeneous catalysts.

Surprisingly, it has now been found that the agglomerates ofnanoparticles having an inorganic core which are described below canadvantageously be employed for catalysts of this type.

The present invention relates firstly to a microparticulate materialcomprising nanoparticulate cores of inorganic material with oligomericor polymeric structures containing non-acidic, nucleophilic groups ontheir surface, where the cores have been agglomerated via interaction ofthe non-acidic, nucleophilic groups with at least one furtherconstituent containing electrophilic groups.

The microparticulate material is preferably a catalyst formed from asupport, at least one catalytically active species and optionally atleast one cocatalyst, which is characterised in that the supportcomprises cores of inorganic material with oligomeric or polymericstructures containing non-acidic, nucleophilic groups on their surface,and the cores have been agglomerated via interaction of the non-acidic,nucleophilic groups with at least one further constituent containingelectrophilic groups.

The term “nanoparticulate” is applied here to all particles whoseaverage mean particle diameter is in the range from about 1 nm to lessthan 1000 nm. Correspondingly, the term “microparticulate” is applied toall particles whose average mean particle diameter is in the range from1 μm to less than 1000 μm.

The further constituents containing electrophilic groups are preferablyat least one catalytically active species or at least one cocatalyst.

The present invention furthermore relates to a nanoparticulate materialcomprising cores of inorganic material, where oligomeric or polymericstructures containing non-acidic, nucleophilic groups are present on thesurface of the cores.

The core of an inorganic material preferably consists of a metal orsemimetal or a metal salt, but particularly preferably a metalchalcogenide or metal pnictide. For the purposes of the presentinvention, the term “chalcogenides” is applied to compounds in which anelement from group 16 of the Periodic Table is the electronegativebinding partner; the term “pnictides” is applied to those in which anelement from group 15 of the Periodic Table is the electronegativebinding partner.

Preferred cores consist of metal chalcogenides, preferably metal oxides,or metal pnictides, preferably nitrides or phosphides. For the purposesof these terms, “metals” are all elements which can occur aselectropositive partner compared with the counterions, such as theclassical sub-group metals or the main-group metals from the first andsecond main groups, but also all elements from the third main group aswell as silicon, germanium, tin, lead, phosphorus, arsenic, antimony andbismuth. The preferred metal chalcogenides and metal pnictides include,in particular, silicon dioxide, zirconium dioxide, titanium dioxide,aluminium oxide, gallium nitride, boron nitride, aluminium nitride,silicon nitride and phosphorus nitride.

For the purposes of the invention, particular preference is given tomicroparticulate or nanoparticulate materials which are characterised inthat the inorganic material of the cores is an oxidic material which ispreferably selected from the oxides of the elements from main groups 3and 4 and sub-groups 3 to 8 of the Periodic Table, particularlypreferably an aluminium oxide, silicon oxide, boron oxide, germaniumoxide, titanium oxide, zirconium oxide or iron oxide, or a mixed oxideor an oxide mixture of the said compounds.

In a variant of the present invention, the starting material employedfor the production of the core/shell particles according to theinvention preferably comprises monodisperse cores of silicon dioxide,which can be obtained, for example, by the process described in U.S.Pat. No. 4,911,903. The cores here are produced by hydrolyticpolycondensation of tetraalkoxysilanes in an aqueous ammoniacal medium,in which firstly a sol of primary particles is produced, and theresultant SiO₂ particles are subsequently converted to the desiredparticle size by continuous, controlled metered addition oftetraalkoxysilane. This process enables the production of monodisperseSiO₂ cores having a standard deviation of the mean particle diameter of5%.

A further preferred starting material comprises SiO₂ cores which havebeen coated with (semi)metals or non-absorbent metal oxides, such as,for example, TiO₂, ZrO₂, ZnO₂, SnO₂ or Al₂O₃. The production of metaloxide-coated SiO₂ cores is described in greater detail, for example, inU.S. Pat. No. 5,846,310, DE 198 42 134 and DE 199 29 109.

A further starting material which can be employed comprises monodispersecores of metal oxides, such as TiO₂, ZrO₂, ZnO₂, SnO₂ or Al₂O₃, ormetal-oxide mixtures. Their production is described, for example, in EP0,644,914. Furthermore, the process of EP 0,216,278 for the productionof monodisperse SiO₂ cores can readily be applied with the same resultto other oxides. Tetraethoxysilane, tetrabutoxytitanium,tetrapropoxyzirconium or mixtures thereof are added in one portion withvigorous mixing to a mixture of alcohol, water and ammonia whosetemperature has been set accurately to from 30 to 40° C. using athermostat, and the resultant mixture is stirred vigorously for afurther 20 seconds, giving a suspension of monodisperse cores in thenanometer range. After a post-reaction time of from 1 to 2 hours, thecores are separated off in a conventional manner, for example bycentrifugation, washed and dried.

The oligomeric or polymeric structures containing non-acidic,nucleophilic groups on the surface of the cores are preferably polymers(where the term “oligomers” below is basically included under the termpolymer) which have been grafted or polymerised onto the surface, i.e.have been synthesised on the surface. The polymers may be branched orunbranched; in a preferred embodiment, the polymers have a linearstructure. The non-acidic, nucleophilic groups here may be presentdirectly in the main chain or can be in the form of functional groups orsmall molecules as a side chain. The polymers may either have beengrafted or polymerised directly onto the optionally functionalisedsurface, i.e. synthesised on the surface, or bonded to the surface via aspacer. In a preferred embodiment of the invention, the spacer is aninert polymer, such as polyethylene, polypropylene or polystyrene, or acyclic or acyclic low-molecular-weight hydrocarbon compound,particularly preferably an alkyl chain having 1-20 carbon atoms. Thepolymer containing non-acidic, nucleophilic groups is preferably apolyether, such as, in particular, polyethylene oxide, polypropyleneoxide or a mixed polymer of ethylene oxide and propylene oxide, orpolyvinyl alcohol, a polysaccharide or a polycyclodextrin.

In accordance with the invention, these oligomeric or polymericstructures are applied to the inorganic cores after the latter have beenformed. The present invention therefore furthermore relates to a processfor the production of a nanoparticulate material which is characterisedin that oligomeric or polymeric structures containing non-acidic,nucleophilic groups are applied to the surface of cores of inorganicmaterial.

In order to apply the oligomeric or polymeric structures to the surfaceof the cores, it may be advantageous, as already stated above, for thesurface of the cores to be functionalised. A process in which thesurface of the cores is functionalised before application of theoligomeric or polymeric structures is therefore preferred for thepurposes of the invention. It may be particularly preferred here toapply to the surface chemical functions which, as active chain end,enable the shell polymers to be grafted on. Examples which may bementioned here are, in particular, terminal double bonds, halogenfunctions, epoxy groups and polycondensable groups. Thefunctionalisation here can take place directly during production of theparticles. In a preferred embodiment, functionalised silicon dioxideparticles are obtained by the method described in EP-A-216 278 throughthe use of trialkoxysilanes which already carry the desired group forsurface functionalisation. The modification of surfaces carryinghydroxyl groups is disclosed, for example, in EP-A-337 144. Furthermethods for the modification of particle surfaces are well known to theperson skilled in the art, in particular from the production ofchromatography materials, and are described in various textbooks, suchas Unger, K. K., Porous Silica, Elsevier Scientific Publishing Company(1979).

The constituents containing electrophilic groups are preferablyorganometallic compounds of a (semi)metal from main group 3 or 4 of thePeriodic Table, which are also referred to below as “cocatalyst”. Theyare particularly preferably a compound of the elements boron, aluminium,tin or silicon, preferably a compound of boron or aluminium. Halide-freecompounds are preferred. The organic radicals of the compounds arepreferably selected from the group consisting of alkyl, alkenyl, aryl,alkaryl, aralkyl, alkoxy, aryloxy, alkaryloxy and aralkoxy radicals andfluorine-substituted derivatives.

Preferred compounds are trialkylaluminium compounds, such astrimethylaluminium, triethylaluminium, tripropylaluminium andtriisopropylaluminium.

Particular preference is also given to aluminoxanes containing alkylgroups on the aluminium, such as methyl-, ethyl-, propyl-, isobutyl-,phenyl- or benzylalumin-oxane, particular preference being given tomethylaluminoxane, which is frequently known by the abbreviation MAO.

It is essential here that the constituent containing electrophilicgroups is selected so that the microparticulate material forms throughinteraction with the nanoparticulate cores. The person skilled in theart is presented with absolutely no difficulties in selectingnucleophilic and electrophilic groups which interact with one another ina corresponding manner.

The microparticulate material is preferably built up from thenanoparticulate cores, with the cores being held together throughinteraction of the non-acidic, nucleophilic groups on the core with theelectrophilic groups of the other constituents. A process for theproduction of a microparticulate material of this type in whichnanoparticulate cores of inorganic material with oligomeric or polymericstructures containing non-acidic, nucleophilic groups on their surfaceare agglomerated with at least one further constituent containingelectrophilic groups is likewise a subject-matter of the presentinvention.

In a particularly preferred embodiment of the present invention, thepolymers containing non-acidic, nucleophilic groups are polyethyleneoxide (PEO), and the further constituent containing electrophilic groupsis methylaluminoxane (MAO). In this case, it is assumed that theagglomerates are formed and stabilised by coordination of the polymerchains of the PEO onto the metal cntres of the MAO. In accordance withthis idea, the microparticulate material is a network of MAO with coreswith PEO-modified surfaces.

The material according to the invention has the following advantagesover the prior art on use as or in a catalyst:

-   -   The catalytically active compounds are homogeneously distributed        on the support.    -   The catalyst fragments uniformly during the reaction.    -   The fragments formed are small and uniformly distributed in the        reaction product.    -   Material properties of polymers prepared with the catalyst        according to the invention are only influenced to a minimal        extent, or not at all, by the small, homogeneously distributed        catalyst fragments.    -   The homogeneous catalyst distribution on the support combined        with the uniform fragmentation produces a uniform course of the        catalysed reaction.    -   The catalyst can advantageously be employed in particular in        reactions, such as polymerisation reactions, in which control of        the heat of reaction represents a technical problem, since heat        peaks are avoided through the uniform course of the reaction.

The above-mentioned advantages can be achieved in a particularlypronounced manner in polymerisation reactions. The catalyst according tothe invention is therefore preferably a polymerisation catalyst or theuse of the catalyst for polymerisation reactions is particularlypreferred in accordance with the invention. In particular, it has beenfound, surprisingly, that the polymers obtained in this way haveimproved material properties compared with the prior art. In particular,advantages arise with regard to:

-   -   the transparency of the polymers    -   the tear strength of the polymers    -   the appearance of the polymers, since inhomogeneities due to        catalyst fragments have been reduced.

In a preferred embodiment of the invention, spherical particles areobtained. Spherical here means that the particles give the impression ofspheres in scanning electron photomicrographs. “Spherical” can bequantified in the sense that the means of the three mutuallyperpendicular diameters of the particles differ from one another by amaximum of 50% of the length. This means that all ratios of the threemutually perpendicular diameters are in each case in the range from1.5:1 to 1:1.5. The ratios of the three mean diameters are preferablyeven all in the range from 1.3:1 to 1:1.3, i.e. the diameters differfrom one another by a maximum of 30%.

The material according to the invention usually has mean particle sizesin the range from 1 to 150 μm, preferably in the range from 3 to 75 μm.The particle-size distribution here can be controlled by classification,for example by air classification. The surface area of theparticles—determined by the BET method (S. Brunnauer, P. H. Emmett, E.Teller, J. Am. Chem. Soc. 1938, 60, 309)—is usually in the range from 50to 500 m²/g, with surface areas in the range from 150 to 450 m²/g beingpreferred. The pore volume, likewise measured by the BET method, istypically in the range from 0.5 to 4.5 ml/g, with the pore volumepreferably being greater than 0.8 ml/g and particularly preferably inthe range from 1.5 to 4.0 ml/g.

The materials according to the invention are suitable as supports for avery wide variety of catalysts. In principle, all homogeneous catalystscan be immobilised with the aid of these materials.

In a particularly important embodiment of the present invention, thematerials are employed as supports for catalysts for the polymerisationof olefins.

Conventional catalyst systems for the polymerisation of olefins consistof a compound of a transition metal from sub-groups 3 to 8 of thePeriodic Table and a co-catalyst, usually an organometallic compound ofa (semi)metal from main group 3 or 4 of the Periodic Table.

The present invention therefore furthermore relates to a heterogeneouscatalyst which comprises at least one nanoparticulate material, asdescribed above, at least one compound of a transition metal fromsub-groups 3 to 8 of the Periodic Table, and at least one organometalliccompound of a (semi)metal from main group 3 or 4 of the Periodic Table,where the transition-metal component and the organometallic componentare bonded to the nanoparticulate material and together form thecatalytically active species.

It is particularly preferred here for the nanoparticulate material andthe transition-metal component or the organometallic component togetherto form a microparticulate material, as described above.

The compound of a transition metal from sub-groups 3 to 8 of thePeriodic Table, which is also referred to below as “catalyst”, ispreferably a complex compound, particularly preferably a metallocenecompound. In principle, this can be any metallocene. Bridged (ansa-) andunbridged metallocene complexes with (substituted) π-ligands, such ascyclopentadienyl, indenyl or fluorenyl ligands, are conceivable here,giving symmetrical or asymmetrical complexes with central metals fromgroups 3 to 8. The central metals employed are preferably the elementstitanium, zirconium, hafnium, vanadium, palladium, nickel, cobalt, ironor chromium, with titanium and in particular zirconium beingparticularly preferred.

Suitable zirconium compounds are, for example:

-   bis(cyclopentadienyl)zirconium monochloride monohydride,-   bis(cyclopentadienyl)zirconium monobromide monohydride,-   bis(cyclopentadienyl)methylzirconium hydride,-   bis(cyclopentadienyl)ethylzirconium hydride,-   bis(cyclopentadienyl)cyclohexylzirconium hydride,-   bis(cyclopentadienyl)phenylzirconium hydride,-   bis(cyclopentadienyl)benzylzirconium hydride,-   bis(cyclopentadienyl)neopentylzirconium hydride,-   bis(methylcyclopentadienyl)zirconium monochloride monohydride,-   bis(indenyl)zirconium monochloride monohydride,-   bis(cyclopentadienyl)zirconium dichloride,-   bis(cyclopentadienyl)zirconium dibromide,-   bis(cyclopentadienyl)methylzirconium monochloride,-   bis(cyclopentadienyl)ethylzirconium monochloride,-   bis(cyclopentadienyl)cyclohexylzirconium monochloride,-   bis(cyclopentadienyl)phenylzirconium monochloride,-   bis(cyclopentadienyl)benzylzirconium monochloride,-   bis(methylcyclopentadienyl)zirconium dichloride,-   bis(1,3-dimethylcyclopentadienyl)zirconium dichloride,-   bis(n-butylcyclopentadienyl)zirconium dichloride,-   bis(n-propylcyclopentadienyl)zirconium dichloride,-   bis(isobutylcyclopentadienyl)zirconium dichloride,-   bis(cyclopentylcyclopentadienyl)zirconium dichloride,-   bis(octadecylcyclopentadienyl)zirconium dichloride,-   bis(indenyl)zirconium dichloride,-   bis(indenyl)zirconium dibromide,-   bis(indenyl)dimethylzirconium,-   bis(4,5,6,7-tetrahydro-1-indenyl)dimethylzirconium,-   bis(cyclopentadienyl)diphenylzirconium,-   bis(cyclopentadienyl)dibenzylzirconium,-   bis(cyclopentadienyl)methoxyzirconium chloride,-   bis(cyclopentadienyl)ethoxyzirconium chloride,-   bis(cyclopentadienyl)butoxyzirconium chloride,-   bis(cyclopentadienyl)-2-ethylhexoxyzirconium chloride,-   bis(cyclopentadienyl)methylzirconium ethoxide,-   bis(cyclopentadienyl)methylzirconium butoxide,-   bis(cyclopentadienyl)ethylzirconium ethoxide,-   bis(cyclopentadienyl)phenylzirconium ethoxide,-   bis(cyclopentadienyl)benzylzirconium ethoxide,-   bis(methylcyclopentadienyl)ethoxyzirconium chloride,-   bis(indenyl)ethoxyzirconium chloride,-   bis(cyclopentadienyl)ethoxyzirconium,-   bis(cyclopentadienyl)butoxyzirconium,-   bis(cyclopentadienyl)-2-ethylhexoxyzirconium,-   bis(cyclopentadienyl)phenoxyzirconium monochloride,-   bis(cyclopentadienyl)cyclohexoxyzirconium chloride,-   bis(cyclopentadienyl)phenylmethoxyzirconium chloride,-   bis(cyclopentadienyl)methylzirconium phenylmethoxide,-   bis(cyclopentadiphenyl)trimethylsiloxyzirconium chloride,-   bis(cyclopentadienyl)triphenylsiloxyzirconium chloride,-   bis(cyclopentadienyl)thiophenylzirconium chloride,-   bis(cyclopentadienyl)neoethylzirconium chloride,-   bis(cyclopentadienyl)bis(dimethylamide)zirconium,-   bis(cyclopentadienyl)diethylamidezirconium chloride,-   dimethylsilylenebis(4,5,6,7-tetrahydro-1-indenyl)zirconium    dichloride,-   dimethylsilylenebis(4,5,6,7-tetrahydro-1-indenyl)dimethylzirconium,-   dimethylsilylenebis(2-methyl-4,5-benzoindenyl)zirconium dichloride,-   dimethylsilylenebis(4-tert-butyl-2-methylcyclopentadienyl)zirconium    dichloride,-   dimethylenesilylbis(4-tert-butyl-2-methylcyclopentadienyl)dimethylzirconium,-   ethylenebis(indenyl)ethoxyzirconium chloride,-   ethylenebis(4,5,6,7-tetrahydro-1-indenyl)ethoxyzirconium chloride,-   ethylenebis(indenyl)dimethylzirconium,-   ethylenebis(indenyl)diethylzirconium,-   ethylenebis(indenyl)diphenylzirconium,-   ethylenebis(indenyl)dibenzylzirconium,-   ethylenebis(indenyl)methylzirconium monobromide,-   ethylenebis(indenyl)ethylzirconium monochloride,-   ethylenebis(indenyl)benzylzirconium monochloride,-   ethylenebis(indenyl)methylzirconium monochloride,-   ethylenebis(indenyl)zirconium dichloride,-   ethylenebis(indenyl)zirconium dibromide,-   ethylenebis(4,5,6,7-tetrahydro-1-indenyl)dimethylzirconium,-   ethylenebis(4,5,6,7-tetrahydro-1-indenyl)methylzirconium    monochloride,-   ethylenebis(4,5,6,7-tetrahydro-1-indenyl)zirconium dichloride,-   ethylenebis(4,5,6,7-tetrahydro-1-indenyl)zirconium dibromide,-   ethylenebis(4-methyl-1-indenyl)zirconium dichloride,-   ethylenebis(5-methyl-1-indenyl)zirconium dichloride,-   ethylenebis(6-methyl-1-indenyl)zirconium dichloride,-   ethylenebis(7-methyl-1-indenyl)zirconium dichloride,-   ethylenebis(5-methoxy-1-indenyl)zirconium dichloride,-   ethylenebis(2,3-dimethyl-1-indenyl)zirconium dichloride,-   ethylenebis(4,7-dimethyl-1-indenyl)zirconium dichloride,-   ethylenebis(4,7-dimethoxy-1-indenyl)zirconium dichloride,-   ethylenebis(indenyl)zirconium dimethoxide,-   ethylenebis(indenyl)zirconium diethoxide,-   ethylenebis(indenyl)methoxyzirconium chloride,-   ethylenebis(indenyl)ethoxyzirconium chloride,-   ethylenebis(indenyl)methylzirconium ethoxide,-   ethylenebis(4,5,6,7-tetrahydro-1-indenyl)zirconium dimethoxide,-   ethylenebis(4,5,6,7-tetrahydro-1-indenyl)zirconium diethoxide,-   ethylenebis(4,5,6,7-tetrahydro-1-indenyl)methoxyzirconium chloride,-   ethylenebis(4,5,6,7-tetrahydro-1-indenyl)ethoxyzirconium chloride,-   ethylenebis(4,5,6,7-tetrahydro-1-indenyl)methylzirconium ethoxide,-   ethylenebis(4,5,6,7-tetrahydro-1-indenyl)dimethylzirconium,-   isopropylene(cyclopentadienyl)(1-fluorenyl)zirconium dichloride,-   diphenylmethylene(cyclopentadienyl)(1-fluorenyl)zirconium    dichloride.

Suitable titanium compounds are, for example:

-   bis(cyclopentadienyl)titanium monochloride monohydride,-   bis(cyclopentadienyl)methyltitanium hydride,-   bis(cyclopentadienyl)phenyltitanium chloride,-   bis(cyclopentadienyl)benzyltitanium chloride,-   bis(cyclopentadienyl)titanium dichloride,-   bis(cyclopentadienyl)dibenzyltitanium,-   bis(cyclopentadienyl)ethoxytitanium chloride,-   bis(cyclopentadienyl)butoxytitanium chloride,-   bis(cyclopentadienyl)methyltitanium ethoxide,-   bis(cyclopentadienyl)phenoxytitanium chloride,-   bis(cyclopentadienyl)trimethylsiloxytitanium chloride,-   bis(cyclopentadienyl)thiophenyltitanium chloride,-   bis(cyclopentadienyl)bis(dimethylamide)titanium,-   bis(cyclopentadienyl)ethoxytitanium,-   bis(n-butylcyclopentadienyl)titanium dichloride,-   bis(cyclopentylcyclopentadienyl)titanium dichloride,-   bis(indenyl)titanium dichloride,-   ethylenebis(indenyl)titanium dichloride,-   ethylenebis(4,5,6,7-tetrahydro-1-indenyl)titanium dichloride and-   dimethylsilylene(tetramethylcyclopentadienyl)(tert-butylamido)titanium    dichloride.

Suitable hafnium compounds are, for example:

-   bis(cyclopentadienyl)hafnium monochloride monohydride,-   bis(cyclopentadienyl)ethylhafnium hydride,-   bis(cyclopentadienyl)phenylhafnium chloride,-   bis(cyclopentadienyl)hafnium dichloride,-   bis(cyclopentadienyl)benzylhafnium,-   bis(cyclopentadienyl)ethoxyhafnium chloride,-   bis(cyclopentadienyl)butoxyhafnium chloride,-   bis(cyclopentadienyl)methylhafnium ethoxide,-   bis(cyclopentadienyl)phenoxyhafnium chloride,-   bis(cyclopentadienyl)thiophenylhafnium chloride,-   bis(cyclopentadienyl)bis(diethylamide)hafnium,-   ethylenebis(indenyl)hafnium dichloride,-   ethylenebis(4,5,6,7-tetrahydro-1-indenyl)hafnium dichloride and-   dimethylsilylenebis(4,5,6,7-tetrahydro-1-indenyl)hafnium dichloride.

Suitable iron compounds are, for example:

-   2,6-[1-(2,6-diisopropylphenylimino)ethyl]pyridineiron dichloride,-   2,6-[1-(2,6-dimethylphenylimino)ethyl]pyridineiron dichloride.

Suitable nickel compounds are, for example:

-   (2,3-bis(2,6-diisopropylphenylimino)butane)nickel dibromide,-   1,4-bis(2,6-diisopropylphenyl)acenaphthenediiminonickel dichloride,-   1,4-bis(2,6-diisopropylphenyl)acenaphthenediiminonickel dibromide.

Suitable palladium compounds are, for example:

-   (2,3-bis(2,6-diisopropylphenylimino)butane)palladium dichloride and-   (2,3-bis(2,6-diisopropylphenylimino)butane)dimethylpalladium.

Particular preference is given here to the use of zirconium compounds,with the compounds bis(cyclopentadienyl)zirconium dichloride,bis(n-butylcyclopenta-dienyl)zirconium dichloride,ethylenebis(4,5,6,7-tetrahydro-1-indenyl)zirconium dichloride,bis(methylcyclopentadienyl)zirconium dichloride andbis(1,3-dimethyl-cyclopentad ienyl)zirconium dichloride beingparticularly preferred.

However, the compound of a transition metal from sub-groups 3 to 8 can,in accordance with the invention, also be a classical Ziegler-Nattacompound, such as titanium tetrachloride, tetraalkoxytitanium,alkoxytitanium chlorides, vanadium halides, vanadium oxide halides andalkoxyvanadium compounds in which the alkyl radicals have from 1 to 20carbon atoms.

In accordance with the invention, it is possible to employ both puretransition-metal compounds and mixtures of various transition-metalcompounds, where both mixtures of metallocenes or Ziegler-Nattacompounds with one another and also mixtures of metallocenes withZiegler-Natta compounds may be advantageous.

The mean particle size of the catalyst particles is usually in the rangefrom 1 to 150 μm, preferably in the range from 3 to 75 μm.

In a preferred embodiment of the invention, the heterogeneous catalystaccording to the invention enables the production of polymer particleshaving a controllable particle size and shape. The particle size herecan be set in the range from about 50 μm to about 3 mm. A preferredparticle shape is the spherical shape, which, as described above, can beproduced by spherical support particles having a particularly uniformcatalyst coating.

The present invention furthermore relates to a process for thepreparation of the heterogeneous catalyst according to the invention inwhich

-   -   a) at least one nanoparticulate material, as described above, is        reacted with at least one organometallic compound of a        (semi)metal from main group 3 or 4 of the Periodic Table, and    -   b) with at least one compound of a transition metal from        sub-groups 3 to 8 of the Periodic Table to give the        heterogeneous catalyst.

The preparation of the heterogeneous catalyst using the nanoparticulatematerial according to the invention can be carried out by variousprocesses, taking particular account of the sequence of the reaction ofthe components with one another:

In a preferred process, the organometallic compound of a (semi)metalfrom main group 3 or 4 of the Periodic Table (referred to below ascocatalyst) is firstly absorbed on the nanoparticulate material (alsoreferred to below as support), and the compound of a transition metalfrom sub-groups 3 to 8 of the Periodic Table (also referred to below ascatalyst) is subsequently added. In another, likewise preferred process,a mixture of catalyst and cocatalyst is reacted with the support. Incertain cases, it may also be preferred for the catalyst firstly to beimmobilised on the support and subsequently reacted with the cocatalyst.In a preferred variant of the process, a microparticulate materialaccording to the invention is formed from the nanoparticulate materialby reaction with the first component of cocatalyst or catalyst.Alternatively, for example, the cocatalyst methylaluminoxane can also beformed in situ by reaction of trimethylaluminium with a water-containingsupport material. Direct chemical bonding of the metallocene catalyst tothe nanoparticulate material with the aid of a spacer or anchor group isalso a possible step in the preparation of the heterogeneous catalyst.

The nanoparticulate material is usually suspended in an inert solvent,and the catalyst and cocatalyst are added as a solution or suspension.After the individual reaction steps, washing with a suitable solvent canbe carried out for purification.

All process steps of the catalyst preparation are preferably carried outunder a protective gas, for example argon or nitrogen.

Suitable inert solvents are, for example, pentane, isopentane, hexane,heptane, octane, nonane, cyclopentane, cyclohexane, benzene, toluene,xylene, ethylbenzene and diethylbenzene.

In a particularly preferred variant of the process according to theinvention, the nanoparticulate material is reacted with an aluminoxane,preferably commercially available methylaluminoxane. In this case, thenanoparticulate material is suspended, for example in toluene, andsubsequently reacted with the aluminium component for about 30 minutesat temperatures between 0 and 140° C. This gives a heterogenisedmethylaluminoxane as microparticulate material. The cocatalyst supportedin this way is subsequently brought into contact with a metallocene,preferably dicyclopentadienylzirconium dichloride, with thecatalyst/cocatalyst ratio being between 1 and 1:100,000. The mixing timeis from 5 minutes to 48 hours, preferably from 5 to 60 minutes.

The actual catalytically active centres of the heterogeneous catalystaccording to the invention do not form until during the reaction of thenanoparticulate material with the catalyst and cocatalyst components.

In accordance with the invention, the heterogeneous catalysts arepreferably employed for the preparation of polyolefins.

The present invention accordingly also relates to the use of aheterogeneous catalyst as described above for the preparation ofpolyolefins.

The term “polyolefins” here is very generally taken to meanmacromolecular compounds which can be obtained by polymerisation ofsubstituted or unsubstituted hydrocarbon compounds having at least onedouble bond in the monomer molecule.

Olefin monomers here preferably have a structure of the formula R¹CH═CHR², where R¹ and R² may be identical or different and are selectedfrom the group consisting of hydrogen and the cyclic and acyclic alkyl,aryl and alkylaryl radicals having from 1 to 20 carbon atoms.

Olefins which can be employed are monoolefins, such as, for example,ethylene, propylene, but-1-ene, pent-1-ene, hex-1-ene, oct-1-ene,hexadec-1-ene, octadec-1-ene, 3-methylbut-1-ene, 4-methylpent-1-ene and4-methylhex-1-ene, diolefins, such as, for example, 1,3-butadiene,1,4-hexadiene, 1,5-hexadiene, 1,6-hexadiene, 1,6-octadiene and1,4-dodecadiene, aromatic olefins, such as styrene, o-methylstyrene,m-methylstyrene, p-methylstyrene, p-tert-butylstyrene, m-chlorostyrene,p-chlorostyrene, indene, vinylanthracene, vinylpyrene, 4-vinylbiphenyl,dimethanooctahydronaphthalene, acenaphthalene, vinylfluorene andvinyl-chrysene, cyclic olefins and diolefins, such as, for example,cyclopentene, 3-vinyl-cyclohexene, dicyclopentadiene, norbornene,5-vinyl-2-norbornene, tert-ethylidene-2-norbornene,7-octenyl-9-borabicyclo[3.3.1]nonane, 4-vinylbenzo-cyclobutane andtetracyclododecene, and furthermore, for example, acrylic acid,methacrylic acid, methyl methacrylate, ethyl acrylate, acrylonitrile,2-ethylhexyl acrylate, methacrylonitrile, maleimide, N-phenylmaleimide,vinylsilane, trimethyl-allylsilane, vinyl chloride, vinylidene chlorideand isobutylene.

Particular preference is given to the olefins ethylene, propylene andgenerally further 1-olefins, which are either homopolymerised oralternatively copolymerised in mixtures with other monomers. The presentinvention accordingly furthermore relates to a process for thepreparation of polyolefins in which use is made of a heterogeneouscatalyst as described above and an olefin of the formula R¹CH═CHR²,where R¹ and R² may be identical or different and are selected from thegroup consisting of hydrogen and the cyclic and acyclic alkyl, aryl andalkylaryl radicals having from 1 to 20 carbon atoms.

The polymerisation is carried out in a known manner by solution,suspension or gas-phase polymerisation, continuously or discontinuously,with gas-phase and suspension polymerisation expressly being preferred.Typical temperatures in the polymerisation are in the range from 0° C.to 200° C., preferably in the range from 20° C. to 140° C.

The polymerisation is preferably carried out in pressure autoclaves. Ifnecessary, hydrogen may be added as molecular-weight regulator duringthe polymerisation.

The heterogeneous catalysts used in accordance with the invention enablethe preparation of homopolymers, copolymers and block copolymers.

As described above, virtually spherical polymer particles having acontrollable particle size can be obtained through suitable choice ofsupport.

The invention therefore also relates to the use of a heterogeneouscatalyst according to the invention or of a heterogeneous catalystprepared in accordance with the invention for the preparation ofpolyolefins having a spherical particle structure.

EXAMPLES

The following abbreviations are used below:

-   MAO methylaluminoxane-   PEO polyethylene oxide-   Monospher® xxx monodisperse silicon dioxide particles having a mean    particle diameter of xxx nm, standard deviation of the mean particle    diameters<5% (Merck KGaA, Darmstadt)

Example 1 Preparation of the Catalyst

a) Functionalisation of the Nanoparticles (Monospheres® 100 (Merck))

60 g of Monospheres® 100 (Merck, average diameter of the spherical SiO₂particles: 100 nm, standard deviation of the mean particle size<5%)(corresponding to 60 g=1 mol of SiO₂) in the form of a 10% by weightethanolic solution are mixed with 4.93 g (20 mmol) of2-(3,4-epoxycyclohexyl)ethylmethoxysilane at 70° C. with vigorousstirring. The dispersion is refluxed for 24 hours. The dispersion issubsequently evaporated to dryness, and the powder is dried overnight at70° C under reduced pressure, giving a surface coverage density of 10μmol/m².

b) Grafting-on of the Polyethylene Oxide Chains

5.25 g of polyethylene oxide 350 (M=350 g/mol) are stirred in 50 ml oftetrahydrofuran together with 100 mg of sodium until the evolution ofgas ceases. The solution is added using a syringe to a suspension of 5 gof Monospher® 100 treated in accordance with Example 1a) intetrahydrofuran. After stirring for one hour, 2 ml of water are added,the Monospher is purified by centrifugation and washing withtetrahydrofuran three times, and subsequently dried.

c) Metallocene Immobilisation

1 g of the PEO-functionalised Monospher from Example 1b) is suspended in20 ml of a solution of methylaluminoxane (MAO) in toluene (c(Al)=1.5mol/l). After stirring for one hour, 3 ml of a solution of 0.31 mmol ofdicyclopentadienylzirconium dichloride in 11 ml of MAO solution intoluene (c(Al)=1.5 mol/l) are added, the mixture is stirred for 30minutes, and the solvent is removed under reduced pressure.

The resultant catalyst has a coverage of 0.028 mmol of metallocene/g ofcatalyst (total weight incl. metallocene and cocatalyst) and an Al/Zrratio of 410. Scanning electron photomicrographs show particle-sizes forthe catalyst particles of about 50 μm.

Example 2 Preparation of the Catalyst

a) Functionalisation of the Nanoparticles (Monospheres® 150 (Merck))

16.1 g of Monospheres® 150 (Merck, average diameter of the sphericalSiO₂ particles: 150 nm, standard deviation of the mean particle size<5%)are suspended in 300 ml of water, and a solution of 2.44 g (12.34 mmol)of trimethoxychloropropylsilane in 25 ml of ethanol is slowly addeddropwise under reflux. The dispersion is refluxed for 24 hours. Thefunctionalised Monospheres are subsequently separated off bycentrifugation. Purification is carried out by suspending in ethanolthree times followed by centrifugation. The resultant powder is driedunder reduced pressure.

b) Grafting-On of the Polyethylene Oxide Chains

2.68 g of polyethylene oxide 350 (M=350 g/mol) are slowly added at 0° C.to 221 mg of sodium hydride in 50 ml of tetrahydrofuran. The mixture issubsequently stirred for a further 30 minutes at 0° C. and for a further30 minutes at 30 room temperature. The solution is added using a syringeto a suspension of 5 g of the chloropropoxy-functionalised Monospher®150 (from Example 2a) in tetrahydrofuran. After stirring for 12 hours,the solvent is removed, and the residue is washed three times withethanol.

c) Metallocene Immobilisation

1 g of the PEO-functionalised Monospher from Example 2b) is suspended in20 ml of a solution of methylaluminoxane (MAO) in toluene (c(Al)=1.5mol/l). After stirring for one hour, 3 ml of a solution of 0.31 mmol ofdicyclopentadienylzirconium dichloride in 11 ml of MAO solution intoluene (c(Al)=1.5 mol/l) are added, the mixture is stirred for 30minutes, and the solvent is removed under reduced pressure.

Example 3 Polymerisation

5 ml of a solution of triisobutylaluminium in hexane (c(Al)=1 mol/l)were introduced into a 1 l steel autoclave. The autoclave was filledwith 400 ml of isobutane and heated to 70° C., and ethene was introducedto a pressure of 36 bar. 70 mg of the catalyst from Example 1 wereintroduced via a pressure lock by means of an excess pressure of argon.The reactor pressure was kept constant at 40 bar during thepolymerisation by means of ethene via a Pressflow controller.

After a polymerisation time of 1 hour, the reaction is terminated byreleasing the pressure. The isobutane evaporates in the process, and thepolyethene remains as free-flowing granules.

Yield: 48.6 g, productivity: 700 g of PE/g of cat.

1. Microparticulate material comprising nanoparticulate cores ofinorganic material with oligomeric or polymeric structures containingnon-acidic, nucleophilic groups on their surface, where the cores havebeen agglomerated via interaction of the non-acidic, nucleophilic groupswith at least one further constituent containing electrophilic groups.2. Microparticulate material according to claim 1 for use as a catalyst,formed from a support, at least one catalytically active species andoptionally at least one cocatalyst, characterised in that the supportcomprises the cores of inorganic material.
 3. Microparticulate materialaccording to claim 1, characterised in that the further constituentscontaining electrophilic groups are at least one catalytically activespecies or at least one cocatalyst.
 4. Nanoparticulate materialcomprising cores of inorganic material, where oligomeric or polymericstructures containing non-acidic, nucleophilic groups are present on thesurface of the cores.
 5. Microparticulate material according to claim 1or nanoparticulate material according to the invention, characterised inthat the inorganic material of the cores is an oxidic material which ispreferably selected from the oxides of the elements from main groups 3and 4 and sub-groups 3 to 8 of the Periodic Table, particularlypreferably an aluminium oxide, silicon oxide, boron oxide, germaniumoxide, titanium oxide, zirconium oxide or iron oxide, or a mixed oxideor an oxide mixture of the said compounds.
 6. Microparticulate materialaccording to claim 1 or nanoparticulate material according to theinvention, characterised in that the oligomeric or polymeric structurescontaining non-acidic, nucleophilic groups on the surface of the coresare polymers, preferably linear polymers, which have been grafted ontothe surface, where the non-acidic, nucleophilic groups may either bepresent directly in the main chain of the polymers or can be in the formof functional groups or small molecules as a side chain. 7.Microparticulate material or nanoparticulate material according to claim6, characterised in that the polymer containing non-acidic, nucleophilicgroups is a polyether, such as, in particular, polyethylene oxide,polypropylene oxide or a mixed polymer of ethylene oxide and propyleneoxide, or polyvinyl alcohol, a polysaccharide or a polycyclodextrin. 8.Microparticulate material or nanoparticulate material according to claim1, characterised in that the surface of the cores has beenfunctionalised with chemical functions which, as active chain end,enable the shell polymers to be grafted on, preferably with terminaldouble bonds, halogen functions, epoxy groups or polycondensable groups.9. Microparticulate material according to claim 1, characterised in thatthe constituents containing electrophilic groups are organometalliccompounds of a (semi)metal from main group 3 or 4 of the Periodic Table,preferably a compound of the elements boron, aluminium, tin or silicon,particularly preferably methylaluminoxane.
 10. Microparticulate materialaccording to claim 1, characterised in that the polymers containingnon-acidic, nucleophilic groups are polyethylene oxide (PEO), and thefurther constituent containing electrophilic groups is methylaluminoxane(MAO).
 11. Microparticulate material according to claim 1, characterisedin that it consists of spherical particles in which all ratios of themeans of the three mutually perpendicular diameters are in each case inthe range from 1.5:1 to 1:1.5, and the mean particle size of thematerial is in the range from 1 to 150 μm, preferably in the range from3 to 75 μm.
 12. Heterogeneous catalyst comprising a) at least onenanoparticulate material according to claim 4, b) at least one compoundof a transition metal from sub-groups 3 to 8 of the Periodic Table, andc) at least one organometallic compound of a (semi)metal from main group3 or 4 of the Periodic Table, where components b) and c) are bonded tothe nanoparticulate material a) and together form the catalyticallyactive species.
 13. Heterogeneous catalyst according to claim 12,characterised in that constituent a) and constituent b) or c) togetherform a microparticulate material according to the invention. 14.Heterogeneous catalyst according to claim 1, characterised in that thecompound of a transition metal from sub-groups 3 to 8 of the PeriodicTable is a complex compound, particularly preferably a metallocenecompound, where the central metal is preferably selected from theelements titanium, zirconium, hafnium, vanadium, palladium, nickel,cobalt, iron and chromium, with particularly preferred central atomsbeing titanium and in particular zirconium.
 15. Process for theproduction of a nanoparticulate material, characterised in thatoligomeric or polymeric structures containing non-acidic, nucleophilicgroups are applied to the surface of cores of inorganic material. 16.Process according to claim 15, characterised in that the surface of thecores is functionalised before application of the oligomeric orpolymeric structures.
 17. Process for the production of amicroparticulate material, characterised in that nanoparticulate coresof inorganic material with oligomeric or polymeric structures containingnon-acidic, nucleophilic groups on their surface are agglomerated withat least one further constituent containing electrophilic groups. 18.Process for the preparation of a heterogeneous catalyst, characterisedin that a) at least one nanoparticulate material according to claim 4 ora material produced according to the invention is reacted with at leastone organometallic compound of a (semi)metal from main group 3 or 4 ofthe Periodic Table, and b) with at least one compound of a transitionmetal from sub-groups 3 to 8 of the Periodic Table to give theheterogeneous catalyst.
 19. Use of a heterogeneous catalyst according toclaim 12 or of a heterogeneous catalyst prepared by a process accordingto the invention for the preparation of polyolefins.
 20. Process for thepreparation of polyolefins, characterised in that use is made of aheterogeneous catalyst according to claim 12 or a heterogeneous catalystprepared by a process according to the invention and an olefin of theformula R¹CH═CHR², where R¹ and R² may be identical or different and areselected from the group consisting of hydrogen and the cyclic andacyclic alkyl radicals having from 1 to 20 carbon atoms.
 21. Process forthe preparation of polyolefins according to claim 20, characterised inthat the polymerisation is carried out as a gas-phase or suspensionpolymerisation.
 22. Use of a heterogeneous catalyst according to claim12 or of a heterogeneous catalyst prepared by a process according to theinvention for the preparation of polyolefins having a spherical particlestructure.